Teses / dissertações sobre o tema "Co-regulators"

Thesis (Ph.D.)--Boston University PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.
Type I collagen overexpression is a major contributor to fibrosis. This thesis investigates the function of two transcriptional co-regulator complexes involved in collagen expression. Interferon γ induces class II transactivator (CIITA), which is a potent activator of major histocompatibility class (MHC) II expression while concomitantly repressing collagen transcription. It was hypothesized that mutation of CIITA would alter the immune response and increase collagen transcription during bleomycin-induced fibrosis. Two CIITA partial knockout strains had decreased macrophage and T cell recruitment after bleomycin injury. Compared to WT, mutant CIITA mice had elevated IL-4 and IL-10 cytokine expression coinciding with decreased lung disease. Since CIITA hypomorphic mice maintained the collagen repression domain, there was equivalent fibrosis as judged by morphology and biochemical quantification of collagen. These studies determined that CIITA mediates injury and inflammatory responses in the lung. Myofibroblasts, characterized by the expression of smooth muscle cell actin (SMA) and collagen, are important regulators of the repair of tissue injury and fibrosis progression. The transcriptional co-activator, myocardin related transcription factor A (MRTF-A) is known to regulate SMA gene expression. It was hypothesized that MRTF-A might also activate expression of type I collagen in fibrotic cells. MRTF-A strongly transactivated type I collagen gene reporters in lung fibroblasts. Expression of a dominant negative MRTF-A or shRNA targeting MRTF-A resulted in a significant reduction in type I collagen synthesis. MRTF-A is known to activate gene transcription via serum response factor (SRF), which binds to CArG boxes within responsive promoters. Analysis of the COL1A2 promoter revealed a non-canonical CArG box [CCAAACTTGG] as well as several specific protein 1 (Sp1) sites that were important for MRTF-A activation. Fibroblasts from MRTF-A knockout mice exhibited impaired myofibroblast differentiation compared to WT controls. These findings indicate that MRTF-A is an important regulator of collagen synthesis in lung fibroblasts and it depends on both SRF and Sp1 to enhance collagen expression. Taken together, these studies identified two important transcriptional co-regulator complexes with potential regulatory roles in lung fibrosis.

Abstract One of the major tasks in cancer research is to understand the regulation of transcription factors that are crucial in controlling cell proliferation, differentiation and apoptosis. To achieve this, transcriptional co-regulators and signaling pathways that control transcription factors have been extensively studied. One good example is the Runx family of proteins and two of their co-regulators, transcription co-activator with PDZ domain-binding motif (TAZ) and Yes-associated protein (YAP). TAZ and YAP are paralogous and serve as either co-activators or co-repressors depending on the cellular context. In an attempt to understand the underlying molecular mechanisms for this dual role in transcription regulation, and especially considering that Yorkie (a Drosophila homologue of YAP) is under control of the hippo kinase pathway, we considered the possibility that TAZ and YAP are the target of this pathway. As such, we sought to test the signaling pathways, including the hippo-like pathway, that regulate the function of TAZ and YAP in mammalian cells. In this thesis research, I first set out to characterize how TAZ, in synergy with the histone acetyltranserase monocytic leukemia zinc finger protein (MOZ), activates Runx-dependent transcription in a signal-responsive manner. Then I used Runx-dependent transcription as a model system to study the regulation of TAZ. I found that both class I and II histone deacetylases interacted with TAZ and repressed its co-activator activity. In addition, TAZ is acetylated by and synergizes with CBP and p300, two paralogous acetyltransferases, to activate transcription. These results suggest that the activity of TAZ is subjected to regulation by acetylation and deacetylation. These results also provide a molecular basis for the hypothesis that TAZ and YAP recruit or release co-repressors in response to cellular stimuli. I then investigated the hippo-like pathway in mammalian cells. Excitingly, I found that the ki
Résumé Un des défis majeurs de la recherche sur le cancer est de comprendre la régulation de certains facteurs de transcription qui jouent un rôle clé dans le contrôle de la prolifération, de la différenciation et de l'apoptose. Pour cette raison, de nombreuses études approfondies sur les corégulateurs et les voies de signalisation ont été menées. Parmi celles-ci, la famille des protéines Runx et deux de leurs corégulateurs, TAZ (transcription co-activator with PDZ domain-binding motif) et YAP (Yes-associated protein) en sont un bon exemple. TAZ et YAP sont des protéines paralogues et agissent comme des coactivateurs ou des corepresseurs en fonction du contexte cellulaire. Puisque Yorkie, l'orthologue de YAP chez la drosophile, est contrôlé par la voie de signalisation de hippo, l'identification de celle qui régule les fonctions de TAZ et de YAP dans les cellules de Mammifères a été menée afin de comprendre les mécanismes moléculaires du double rôle de ces corégulateurs dans la régulation transcriptionnelle. Dans ce travail de thèse, la manière dont TAZ active la transcription dépendante de Runx, en synergie avec l'histone acétyltransférase MOZ (monocytic leukemia zinc finger protein) a été étudiée. Par la suite, la transcription médiée par Runx a été utilisée comme modèle afin d'étudier la régulation de TAZ. Il a ainsi été démontré que les histones deacétylases de classe I et II interagissent avec TAZ et répriment son activité de coactivateur dans la transcription dépendante de Runx. En outre, TAZ est acétylé par CBP/p300, deux acétyltransférases paralogues, et synergise avec ces deux protéines pour activer la transcription. Ces résultats suggèrent donc que l'activité de TAZ est régulée par un mécanisme d'acétylation et de déacétylation et que TAZ et YAP recrutent et relâchent des corépresseurs en réponse à différents stimuli cellulaires. À la lumière de ces informations, la voie de sig

Le muscle squelettique (MS) est un tissu métabolique important. L'objectif de ma thèse était de caractériser le rôle des corégulateurs de la transcription, PGC-1β (transcriptional coactivator peroxisome proliferator-activated receptor-gammacoactivator 1beta) et TIF2 (Transcriptional Intermediary Factor 2) dans ce tissu. Mon travail a démontré que PGC-1β limite le stress oxydatif est crucial dans le maintien de la structure et de la fonction mitochondriale, via le contrôle de l’expression de gènes impliqués dans les voies de signalisation liées à l’énergie, à la dynamique mitochondriale et à la machinerie d’import mais n'est pas indispensable pour le contenu mitochondrial. Mon travail aussi démontré que TIF2 de la MS a un impact négatif sur la durée de vie des mammifères. De plus, la déplétion de TIF2 conduit à une protection partielle du MS contre les dommages oxydatifs induits par le stress. Ainsi notre travail représente une avancée dans l’établissement futur de traitements contre les troubles liés au stress oxydatif et au vieillissement
Skeletal muscle (SM) accounting for ~ 40% of total body mass is an important metabolic tissue. The aim of my thesis was to characterize the role of transcriptional coregulators, peroxisome proliferator-activated receptor-gamma coactivator-1β (PGC-1β) and transcriptional intermediary factor 2 (TIF2) in this tissue. My work demonstrated that PGC-1β is crucial to maintain SM mitochondrial structure and function, by controlling expression of genes involved in energy pathways, mitochondrial dynamics and import machinery, but is dispensable for mitochondrial content and fiber type maintenance. Furthermore, it limits oxidative stress. The second part of my work demonstrated that myofiber TIF2 has negative impact onmammalian life span. Moreover, TIF2 ablation leads to partial protection of SM from oxidative stress-induced damage. In conclusion, our work provides a better understanding of SM homeostasis regulation and insights in treatments for disordersrelated to oxidative stress and aging

Thesis (Ph. D.) -- University of Maryland, College Park, 2004.
Thesis research directed by: Molecular and Cell Biology. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Thesis (M.S.)--University of California, San Diego, 2009.
Title from first page of PDF file (viewed September 15, 2009). Available via ProQuest Digital Dissertations. Includes bibliographical references (p. 58-61).

The subject matter of this thesis is a regulatory innovation termed co-regulation: a mode of regulation that includes formal involvement of both state and non-state actors. Its emergence and development is the result of two broad and significant changes in the nature of the statehood: the emergence of the regulatory state and the shift from government to governance. In the regulatory state, the dominant mode of intervention in economy and society is regulation, thus forms such as co-regulation are used to ‘govern’ or ‘steer’ the society. In addition, with the shift to governance, there is a greater reliance on non-state actors to perform this ‘steering’. Since co-regulation is used to implement public policy objectives, which has traditionally been the role of government departments, but it implies formalized and substantive role of non-state actors, it is a qualitatively new regulatory development that justifies research interest into its nature. Consequently, it should be evaluated as any other form of governance: to what extent it can be described as democratic, and precisely this is the basis for the normative framework developed for this thesis that has been used as a tool to evaluate the nature and quality of co-regulation. One of the basic premises of this research is that any form of governance should have as its ultimate goal the achievement of public interest objectives. It has been further argued that public interest objectives can be achieved only if institutional structures of regulatory bodies enable transparency, deliberative participation by the citizens, and enable citizens to hold the regulators to account. Only by providing such structures, co-regulatory bodies would empower the citizens to be the ultimate authority and could thus be considered a democratic form of governance. The case studies chosen to evaluate whether this normative ideal has been achieved in practice comprise three different bodies: Ofcom, ASA and ATVOD. What has in particular been looked at is the way Ofcom handled the delegation of regulatory functions to ASA and ATVOD, and the way these bodies dealt with the regulation of 3 alcohol ads and product placement. These studies involve an element of controversy and conflicting interests and as such represent the most suitable test in order to determine whether the possibilities offered by co-regulation to be a truly democratic form of governance have been achieved. The main conclusion reached is that, mainly due to NPM reforms, citizens are confined to the role of the consumers, where their active engagement is seen in terms of complaints and regulators are held accountable for the level of service they provide in handling these complaints. However, this does not empower the citizens. Therefore, it appears that Ofcom, ASA and ATVOD are not characterized by institutional structures that would enable democratic governance: there are no transparent institutional structures that would enable the public to perform the role of the citizens and deliberate regarding regulatory decisions and hold Ofcom, ASA and ATVOD to account. The institutional structures modelled on the premises of corporate governance are not empowering citizens, but are instead creating consumers.

Le récepteur Estrogen-Related Receptor (ERRα), un récepteur nucléaire orphelin intervient dans le métabolisme, la migration et l’invasion cellulaire, l’établissement de métastases et la progression des cancers du sein d’une manière dépendante de corégulateurs. Ma thèse vise à explorer l’activité transcriptionnelle de ERRα au cours de la progression cancéreuse ainsi que les voies pathologiques et physiologiques mises en œuvre. A ces fins : 1- Nous avons prédit les corégulateurs de ERRα en utilisant un algorithme mathématique, l’algorithme de régression adaptive sparse partial least squares (sPLS). Nos résultats montrent que ZEB1 est le plus robuste coactivateur potentiel de ERRα. Nous avons validé que ces deux facteurs corégulent l’expression de huit cibles transcriptionnelles (Differentially Expressed Genes ; DEGs), spécifiquement dans les cellules de cancer du sein triple négatives (TNBC). 2- Nous avons ensuite analysé les mécanismes par lesquels ces deux facteurs corégulent l’expression génique. Nos résultats montrent que la régulation de l’expression des 8 DEGs par ERRα dépend de ZEB1, mais pas d’autres corégulateurs transcriptionnels. No analyses par ChIP montrent que ERRα se fixe directement (i.e. indépendamment de ZEB1) sur les promoteurs des DEGs, alors que ZEB1 requiert la présence de ERRα pour se fixer sur ces mêmes éléments promoteurs. Ceci suggère une interaction physique entre les deux facteurs, que nous avons confirmé par proximity ligation assay. 3- Nous avons ensuite exploré les conséquences pathologiques de ces interactions dans les tumeurs du sein. Nous avons observé une corrélation entre l’état de transition épithélium-mésenchyme (EMT) des tumeurs et l’expression de ZEB1 et des 8 DEGs. Comme l’EMT est corrélée aux métastases des cancers du sein, nous avons ensuite analysé la capacité pronostiques de l’expression des 8 DEGs. Nos résultats montrent que la forte expression des 8 DEGs prédit la survie des patients TNBC. En conclusion, nous avons identifié et validé expérimentalement un nouveau co-activateur (ZEB1) de ERRα impliqué dans la progression des cancers du sein. Ces deux facteurs agissent ensemble sur la régulation transcriptionnelle de gènes impliqués dans l’établissement de métastases et dont l’expression prédit le devenir clinique des patients TNBC
Estrogen-related receptor alpha (ERRα), an orphan nuclear receptor, participates in metabolism, cell migration, cell invasion, metastasis and progression of breast cancer in a coregulator-dependent manner. My thesis aims to explore the transcription activity of ERRα in breast cancer progression as well as the potential pathological and physiological pathways it may be involved in. To achieve this: (1) We firstly predicted co-regulators for ERRα, using a mathematical algorithm, namely adaptive sparse partial least squares (sPLS) regression algorithm. Our results showed that ZEB1 is the most robust potential co-activator of ERRα. We validated that these two factors co-regulate the expression of eight migration-related targets (8 DEGs), specifically in triple negative breast cancer (TNBC) cells. (2) We then investigated the mechanisms through which these two factors co-regulate gene expression. Our results showed that regulation of the expression of the 8 DEGs by ERRα depends on ZEB1, but not on other transcriptional regulators. ChIP analysis showed that ERRα directly (i.e. in a ZEB1-independent manner) binds to the promoters of the DEGs, whereas ZEB1 requires ERRα to bind to the same promoter elements. This suggests a physical interaction between these factors, that was demonstrated by proximity ligation assays. (3) We next explored the pathological consequences of these interactions in breast tumors. We observed a correlation between the state of epithelial to mesenchymal transition (EMT) of the tumors and expression of ZEB1 and the 8 DEGs. Since EMT is correlated with breast cancer metastasis, we next investigated the prognosis ability of the 8 DEGS. Our results show that a high joint expression of the 8 DEGs predicts overall survival in TNBC patients. In conclusion, we identified and experimentally validated a novel co-activator of ERRα involved in breast cancer progression. These two factors act together on the transcription regulation of genes that are highly involved in cancer metastasis and are their expression predicts the clinical outcome of TNBC patients

碩士
國立臺灣大學
分子醫學研究所
90
Wnt molecules control numerous developmental processes by altering specific gene expression patterns, and deregulation of Wnt signaling may lead to cancer. Upon Wnt stimulation, β-catenin accumulates and interacts with T cell factor/Lymphocyte enhancer binding factor (Tcfs) to activate target genes. Tcfs are required for establishing the embryonic body plan, specifying cell fate, and regulating cell proliferation and survival. Intriguingly, Tcfs participate in these cellular processes in a bimodal fashion: activating processes in one subset of cells, while simultaneously repressing the same function in a different subset. In search of additional regulatory cofactors of Lef1, we performed yeast two-hybrid screening using Lef1-△N105 as bait. Three proteins, ZF1, KIAA0941and HIPK3, were identified. The full-length of ZF1, KIAA0941 and HIPK3 were shown to interact with full-length lef1 in GST pull-down assays. KIAA0941 was shown to interact with Lef1 and repress Lef1-driven transcriptional activity in vivo.

Background: The estrogen receptor (ER) signaling pathway is the dominant driver of cell proliferation and survival in the majority of human breast cancers. Not surprisingly, endocrine treatment, such as the anti-estrogen tamoxifen, represents the most effective and widely used therapy for ER positive breast cancer patients. Unfortunately not all patients respond to endocrine treatment and a wide proportion of patients ultimately develop resistance and die. Selecting patients with an increased risk of recurrence and identifying those that might benefit from a particular therapy is of great value in order to personalize breast cancer therapies. A minority of breast cancers does not express ER and displays features of aggressiveness and poor prognosis. Prognostic markers are urgently needed for this subset of patients as well. The p160 family of ER co-activator is composed of three different members: SRC1, SRC2 and AIB1. SRC1 and AIB1 are frequently overexpressed in breast cancer and appear to be linked to hormone resistance, particularly in HER2 positive breast cancer. SMRT is an ER co-repressor that has been implicated in tamoxifen resistance. Data on p160 family members and SMRT expression in human breast cancer samples and its prognostic and predictive significance in endocrine treated patients are controversial or lacking altogether. Moreover, the role of these co-regulators in ER negative disease is poorly understood. Methods: SRC1, SRC2, AIB1 and SMRT expression was determined by immunohistochemistry on tissue microarrays derived from two fully documented cohorts of 1812 and 1424 patients. Results: HER2 and AIB1 dual-positive tumors were associated with markedly worse outcome compared to tumors overexpressing either HER2 or AIB1 alone, irrespective of ER status. In ER negative disease both SRC1 and AIB1 were linked to early relapse and death. Additionally, we found that co-expression of two or more SRCs were significantly associated with worse outcome in ER positive endocrine-treated patients. However, expression of any SRC alone was not a significant predictor of resistance to endocrine therapy. Low nuclear SMRT expression was associated with a significantly better outcome in untreated patients but not in tamoxifen-treated patients. Conclusions: The SRC family of ER co-activators and nuclear SMRT are markers of early relapse in both ER negative and ER positive breast cancer. Evaluation of multiple markers co-expression (i.e. AIB1/HER2, multiple SRCs) rather than single markers allows a better assessment of breast cancer prognosis.